Conventionally, a ship is known having an inboard motor (inboard engine, outboard drive) in which a pair of left and right engines are arranged inside a hull and power is transmitted to a pair of left and right outdrive devices arranged outside the hull. The outdrive devices are propulsion devices rotating screw propellers so as to propel the hull, and are rudder devices rotated concerning a traveling direction of the hull so as to make the hull turn.
Such outdrive devices are rotated with hydraulic steering actuators provided in the outdrive devices (for example, see the Patent Literature 1). Then, a rotation angle of each of the outdrive devices, that is, a steering angle is grasped based on detection results of an angle detection sensor and the like provided in a linkage mechanism constituting the outdrive device.
The ship has an operation means setting a traveling direction of the ship. The ship is controlled with a control device so as to travel to the direction set with the operation means.